Blend all ingredients for the cashew sour cream until smooth and chill in the fridge while you prepare the rest of the salad.

Put the walnuts in a food processor or high-speed blender, and process until chunky. Scrape the ground nuts into a bowl, and mix in the cumin, coriander, chili powder, and cayenne. Add the tamari and mix again.

Make a salsa by mixing the chopped tomatoes, onion, cilantro, and lemon juice. Arrange the chopped romaine in your favorite serving bowl and spoon the taco filling on top. Add the salsa and top off with sour cream and avocado slices, fanned out.